Vapor lock '41 P12

Jim Yergin · May 07, 2013, 09:55:21 AM

Quote from: BruceB on May 06, 2013, 09:39:56 PM
Thanks Jim. Will the new coil fit in the place of the old one, or do I need to intall a bracket?

Bruce,
It depends. If on your old coil the mounting bracket is attached to the old coil, you will have to find another mounting bracket without a coil. I found mine on eBay and the new coil is mounted in the firewall like the old one.
Jim

TodFitch · May 07, 2013, 12:38:07 AM

Quote from: BruceB on May 06, 2013, 09:39:56 PM
Thanks Jim. Will the new coil fit in the place of the old one, or do I need to intall a bracket?

There used to be aftermarket coils that were packaged with a clamp that had the three hole for bolting to the firewall and holding a conventional coil in place. If your current coil is being held by one of those, then re-use it. If not. . . Well, I guess you could make one. But it might be easier to find a regular coil mounting clamp and just install it in a convenient location.

BruceB · May 06, 2013, 09:39:56 PM

Thanks Jim. Will the new coil fit in the place of the old one, or do I need to intall a bracket?

Jim Yergin · May 06, 2013, 10:29:45 AM

Bruce,
I have installed a new style coil in my '41 Plymouth. It only requires that you extend the wire that is now attached to the bottom of your old coil and run that wire out into the engine compartment where it connects to the negative terminal on the coil.
Jim Yergin

BruceB · May 05, 2013, 04:34:54 PM

:-[ Sorry it has been so long since i have gotten back on this, but other things (including a lost UserID and password) have kept me away. After reading the replies I got I think that the problem cannot be vapor lock. The stall and no start problem occurs under all the wrong conditions for it to be vapor lock. No long periods of driving in hot weather. Actually, what has happened is this: I start the car (no problem) and let the engine come to normal temperature, then take it for a short spin about a mile down the road, turn around and drive back, pull in the driveway. As soon as I stop in the driveway, the car dies and won't restart for about 20 minutes. I am thinking coil here, and since I want to replace it anyway, along with new plug wires, I bought a new one. But the new is not like the old one at all, which mounts through the firewall and appears to have one of the connections (for the ignition switch cable) on the back end. The replacement I got has the more familiar pos and negative terminal on the front of the coil. The place I bought the coil from said they do not sell new old stock coils since they have a high failure rate. So will this new coil work for me? Is the ignition switch cable a special connection as the wiring diagram seems to show? Thanks.

Bruce

captbrian41 · February 16, 2013, 05:18:07 PM

seems to me that even if the gas in the tank got to be the outside ambient temps. the fuel wouldn't vaporize till it picked up the extra BTU's associated with the lines passing close to a hot block or manifold in the 200 deg. neighborhood. That's where the fuel would start to bubble and not in the tank or the suction side of the pump. So protecting the fuel lines from the pump to the carb and the carb bowl from overheating would be paramount if you are experienceing vapor lock and certainly the easiest to address at first. My efforts would be in protecting the fuel lines or rerouting them initially and then proceed from there on. If you have any qualms about the loosened head bolt and you have a torque wrench you can retighten it to about 60 ft. lbs and it should not cause you any grief.
Brian K.

TodFitch · February 15, 2013, 11:17:12 AM

Quote from: plym_46 on February 15, 2013, 12:13:23 AM
Please tell us what you know about vapor lock. What are the symptoms? Because with my understanding of the laws of fluid dynamics, it's not possible for a bubble of air or gasoline vapor to block a fluid under pressure moving in a tube toward the atmosphere. If it was possible, how do you explain the ability to bleed your hydraulic brakes??? The fuel pump is located at about the same level as the fuel tank, so gravity pretty much assures that fuel will flow to the fuel pump. If the pump is working properly and pumping only fuel it should be able to overcome any bubbles from the pump to the carburetor, as the carburetor float bowl is vented to the atmoshpere.

If the fuel pump is trying to pump air from the tank side of the pump it will not pump properly but that is not vapor lock. Its probably air infiltration of the fuel line between the pump and the tank. Have you done a fuel quantity or pressure test on the pumps output? Do you know the condition of the rubber line that feeds the pump from the steel line coming from the tank?

Can you post some pictures of your current fule lin and how it is routed from the pump to the carb?

The only times I have experienced "vapor lock" I was successfully able to get the car going again by pouring water on the fuel pump. My take away was the 100?F fuel in the gas tank (this only happens to me on very hot days) was already very near to the point where it would vaporize and the heat soak on the pump (only happens to me on hot restart or, rarely, while idling) took the fuel to the point where it vaporized inside the fuel pump. And the pump is nowhere near as good a pump for vapor as it is for liquid. Pouring some drinking water (probably also near 100?F) on the pump cooled it enough that it could start pumping again. Once moving there seems to be enough air flow to keep things under the critical temperature.

My car does not have the fuel pump heat shield that was fitted on later cars. And I suspect there was a reason the factory fitted that piece of metal. . .

captbrian41 · February 15, 2013, 08:48:24 AM

there is a great explanation of automotive vapor lock on yahoo search, but basically it is the boiling of your fuel in the steel lines near your engine or manifolds that absorb heat from those sources. This causes the engine to surge at speed and then making it hard to start if shut down. You can insulate the lines with almost anything that reflects heat in their present location which will help but relocation seems to be the best answer for our vehicles since we have greater access to the fuel line.
Brian K.

plym_46 · February 15, 2013, 12:13:23 AM

Please tell us what you know about vapor lock. What are the symptoms? Because with my understanding of the laws of fluid dynamics, it's not possible for a bubble of air or gasoline vapor to block a fluid under pressure moving in a tube toward the atmosphere. If it was possible, how do you explain the ability to bleed your hydraulic brakes??? The fuel pump is located at about the same level as the fuel tank, so gravity pretty much assures that fuel will flow to the fuel pump. If the pump is working properly and pumping only fuel it should be able to overcome any bubbles from the pump to the carburetor, as the carburetor float bowl is vented to the atmoshpere.

If the fuel pump is trying to pump air from the tank side of the pump it will not pump properly but that is not vapor lock. Its probably air infiltration of the fuel line between the pump and the tank. Have you done a fuel quantity or pressure test on the pumps output? Do you know the condition of the rubber line that feeds the pump from the steel line coming from the tank?

Can you post some pictures of your current fule lin and how it is routed from the pump to the carb?

BruceB · February 14, 2013, 02:56:36 PM

So, the bolts that hold the air filter bracket and the wire loom bracket ARE the headbolts? I loosened one then thought better of it and retightened it. Will this cause me any grief?

captbrian41 · February 14, 2013, 01:43:07 PM

Bruce I have a p-11 TPC and the brackets you talk about attach on the drivers side of the engine on the headbolts, namely the air filter bracket and the wire loom bracket. My fuel line is routed on the passengers side from the fuel pump outside of the manifolds to the carburetor and includes an inline filter attached to the steel tubing with fuel line hose and clamps. There is enough space between the fuel line and manifolds to prevent transfer of heat to the fuel line. I haven't experienced vapor lock and I drive in 100 deg. temps here in eastern NC in the summer to and from cruiseins and shows. As John mentions you might just want to reroute the fuel line which can be easily accomplished with new tubing or by cutting and rebending your old tubing and adding an inline filter and appropiate fuel line hose.
Brian K.

John Hendricks · February 13, 2013, 11:45:57 AM

One can buy suitable diameter steel line with fittings attached at NAPA. I comes in straight lengths. Just figure out how long u need, and then use brake line benders to form a new line. U can even pick up a fuel filter there also and include it in the new fuel line. Be sure u pick up two lines, so when u screw up the first one, u won't have to make the obligatory second trip back to the store.

BruceB · February 11, 2013, 07:34:17 PM

Hi I am the owner of '41 P12 Special deluxe and I have a lot of questions. I was hoping someone out there would be willing to help. First question is this. I have a car that suffers from vapor lock (as the owner of a '65 Corvair Monza back in the day, I know what vapor lock is). But in this case it not only occurs on hot days but even in cool weather. I think I have found the reason. Several inches of the gas line actually touch the engine block. I want to move it away, but there is a bracket that holds the bracket from the oil bath air cleaner that is in the way (this bracket also holds the bracket that separates the plug wires). It looks like the nuts that hold this bracket in place are also head bolts. is this correct? can I remove one or more of those bolts to get the gas line off the block?
I have other questions but will ask them one at a time. Thanks!

Bruce